Police investigating a murder possibly linked to a fire which killed a family have arrested a man and two women, they said tonight.
The three, all aged 19, have been held over the killing of a man in his 20s in Leicester yesterday. Police said the man was arrested in London.
Police believe the family may have been killed in a revenge attack, which neighbours believe may have been a case of mistaken identity.
Shehnila Taufiq, who was in her 40s, died along with her 19-year-old daughter and sons, aged 17 and 15, when their home was engulfed in flames early today.
The mother and her children, named by the local mosque in Leicester as Zainab, Jamal and Bilal, died in their bedrooms at their terraced house in Wood Hill in the Spinney Hills area of the city several hours after a man was killed in nearby Kent Street.
Mrs Taufiq's neurosurgeon husband, Dr Muhammad Taufiq Al Sattar, is believed to be on his way home from Ireland, where he works.
Police have said they cannot rule out a link between the two events and they are investigating whether the fire was started intentionally as a revenge attack.
Neighbours of the family reacted with disbelief to the idea that they could have been intentionally killed - and claimed they may not have been the intended target.
A middle-aged man, who did not want to be named, said: "Most people feel this was meant for somebody else and they got the wrong house."
Leicestershire Police has not confirmed the identities of the five victims.
The force launched its first murder inquiry shortly after 5.30pm yesterday when a man in his 20s was taken from Kent Street - half a mile away from the scene of the fire - to Leicester Royal Infirmary, where he died.
A second inquiry began when neighbours reported flames shooting out of the first floor of the Taufiq family home at 12.30am.
Assistant Chief Constable Roger Bannister said officers were investigating a theory that Mrs Taufiq and her children were killed in revenge for the earlier attack.
He said: "I can't confirm here and now it is a revenge attack - it may be, it may not be - but lines of inquiry will certainly get to the bottom of that."
Urging witnesses to get in touch, he said it was possible that both offences, which he described as "terrible, terrible crimes", were linked.
The Jame Mosque attended by the Taufiq family issued a statement expressing shock at the deaths.
Mr Sattar is a consultant neurosurgeon and has been working in Beaumont Hospital in Dublin and with private hospitals in the city, the Blackrock and Hermitage clinics.
His family lived with him for a number of years before moving to Leicester.
Colleagues at Beaumont Hospital, Blackrock and the Hermitage expressed their sympathy.
Leicester-based Imam Ibrahim Mogra, assistant secretary general of the Muslim Council of Britain, visited the scene.
He said: "It's hard to believe that such a tragedy could occur and four lives could be lost in a matter of minutes."
Local shopkeeper Sattar Raidhan, who has lived in the area for 35 years, said: "I can't even imagine how this would happen to a family like that."
Labour MP Keith Vaz, who represents Leicester East, met local people near the police cordon sealing off Wood Hill.
He said: "If indeed people have deliberately done this, then I'm sure the police will do everything they can in order to catch them and to bring them to justice."
The force has drafted in extra officers and forensics staff to probe both crimes and increased patrols in the area.
The family is originally from Pakistan and had a home in Ireland for at least 15 years.
It is understood Mr Sattar's wife was a qualified doctor but was not working.
The family, prominent figures in the Muslim community, was together about a month ago spending the festival of Ramadan in Ireland.
The children moved to the UK with their mother about five years ago for Islamic education which is not available in Ireland but returned regularly to be with their father at the family home in the Castleknock area of the Irish capital.
Dr Ali Saleem, of the Islamic Cultural Centre in Dublin, said the family planned to reunite in Ireland after the children finished their education.
Mr Vaz later returned to the scene, having spoken with Mr Sattar, and said: "He is obviously in a state of shock over what has happened and I conveyed to him the love and affection of this very close-knit community."
He added: "Putting yourself in his position, you go off to work to save lives as a doctor and you arrive home and find your wife and two sons and daughter are all dead in the most horrible of circumstances. It's absolutely terrible."
Police said the victim of the Kent Street murder had not yet been formally identified.
Forensic examination of the fire scene and the surrounding street is under way.
Police said in a statement: "The whole area is being carefully examined which may take some time. Specially-trained officers will be searching for evidence connected to the incident and this requires careful searching under and around vehicles parked in the street, front gardens and pavements.
Detectives would like to thank the residents of Wood Hill for their patience and co-operation while this is ongoing."